The enhanced optical fields near the surface of illuminated nanostructures form the basis of sensitive analytical methods that include SERS, tip-enhanced Raman spectroscopy (TERS), and surface enhanced infrared absorption. These methods exploit a surface plasmon resonance condition of special metallic nanostructures.
Early SERS efforts were based on rough silver electrodes. This was extended to gold and other metal nanostructures that were engineered to optimize the surface plasmonic interactions. In addition to surface plasmon resonance, there are other polariton resonance conditions that yield enhanced electric fields near the surface of illuminated nanostructures. Surface phonon resonance also provides enhanced optical fields near the surface of illuminated dielectric particles and is used for surface enhance infrared absorption spectroscopy. This is a part of a larger general effort to couple light into small device structures for photonic applications and for sensitive chemical analysis.
Conventional SERS applications use metal nanostructures. However, SERS applications that use electrides rather than metals may be beneficial.